(a) Field of the Invention
The present invention relates to a manufacturing method of a structure having a hydrophobic inner surface, and more particularly, to a manufacturing method of a three dimensional structure in which a surface treatment process and a replication step are performed to provide hydrophobicity to an inner surface of any three dimensional structure.
(b) Description of the Related Art
Generally, a surface of a solid body formed of a metal or a polymer has an inherent surface energy, which is shown by a contact angle between the solid body and a liquid when the liquid material contacts the solid material. The liquid may include water, oil, and so forth, and hereinafter, water will be exemplified as the liquid. When the contact angle is less than 90°, hydrophilicity, in which a sphere shape of a water drop is dispersed on a surface of the solid body to wet the surface, is shown. In addition, when the contact angle is greater than 90°, hydrophobicity, in which the sphere shape of the water drop is maintained on the surface of the solid body to run on the surface, is shown. As an example of hydrophobicity, a water drop that runs on the surface of a leaf of a lotus flower flows without wetting the leaf.
Further, when the surface of a solid body is processed so as to have slight protrusions and depressions, the contact angle of the surface may vary. That is, when the surface is processed, the hydrophilicity of a hydrophilic surface with a contact angle that is less than 90° may increase, and the hydrophobicity of a hydrophobic surface with a contact angle that is greater than 90° may increase. The hydrophobic surface of the solid body may be variously applied. When the hydrophobic surface is applied to a pipe, the liquid flowing through the pipe may easily slip along the pipe, and therefore the amount and speed of the liquid increases. Accordingly, accumulation of foreign materials may be reduced. In addition, when non-wetting polymer materials are used for the hydrophobic surface, corrosion in a pipe is prevented and water contamination may be reduced.
However, technology for varying the contact angle of the surface of the solid body in response to a specific purpose has depended on a micro electro mechanical system (MEMS) process applying a semiconductor fabrication technology. Therefore, this technology is generally used for a method for forming nano-scale protrusions and depressions on the surface of the solid body. The MEMS process is an advanced mechanical engineering technology applying semiconductor technology. However, the apparatus used for the semiconductor process is very expensive. In order to form the nano-scale protrusions and depressions on a surface of a solid metal body, a variety of processes, which cannot be performed under a normal working environment, such as a process for oxidizing the metal surface, a process for applying a constant temperature and a constant voltage, and a process for oxidizing and etching using a special solution, must be performed. That is, in order to perform such processes, a specifically designed clean room is required and a variety of expensive apparatuses for performing the processes are necessary. Furthermore, due to a limitation of the semiconductor process, a large surface cannot be processed at once.
As described above, according to the conventional technology for forming the hydrophobic surface, the process is very complicated and it is difficult to mass-produce products. Furthermore, the cost for producing the products is very high. Therefore, it is difficult to apply the conventional technology.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.